Breathing pattern--gas exchange relation and acute effect of almitrine in severe chronic airflow obstruction

Using a double-blind cross-over design, a single oral dose of 100 mg almitrine bismethylate and placebo were administered to 7 patients with chronic airflow limitation. In all patients, arterial blood gases at rest, ventilation and breathing pattern at rest and on exercise were measured before and 3 h after administration. Ventilation increased and PaCO2 decreased after almitrine; the mean PaO2 increase was statistically significant after active drug but the value increased more when tidal volume increased. It is concluded that in man the well-documented improvement in the V/Q relationship after almitrine is in part related to a pure ventilatory effect though the possibility of increasing ventilation by mainly increasing tidal volume.